Composite carbonaceous member for furnace conveyor units or the like



June 5, 1962 NITZ 3,037,756

N. B. OR COMPOSITE CARBONACEOUS MEMBER FOR FURNACE CONVEYOR UNITS OR THE LIKE Filed Sept. 22, 1959 2 Sheets-Sheet 1 26 INVENTOR.

Noihuniel B. Ornitz I 27 W /Wf 29 R V June 5, 1962 NlTZ 3,037,756

N. B. OR COMPOSITE CARBONACEOUS MEMBER FOR FURNACE IKE CONVEYOR UNITS OR THE L Filed Sept. 22, 1959 2 Sheets-Sheet 2 Ncnhuniel B. Ornitz V/ rates Unite This invention relates to a composite carbonaceous member for surfacing furnace conveyor units or the like. More particularly, this invention pertains to a composite carbon-and-metal member to supportably engage metal work in strip, sheet and/or plate form at elevated temperatures and in varying furnace atmospheres while inhibiting development of the so-called pickup phenomenon, undue Wear and untimely breakdown of such surfacing member. This application is in part a continuation of my abandoned application Serial No. 571,474, filed March 14, 1956.

The phenomenon of so-called pickup, which has occurred in some heat-treating furnaces in connection with certain metal work, has been known for some time and much effort and expense have been incurred to try to prevent its occurrence which has been particularly severe at relatively elevated temperatures (usually above 1660 F.) in the heat treating of ferrous sheets and strip such as silicon steels and stainless steels. The pickup phenomenon has also caused difficulty in the heat treating of non-ferrous metals such as brass, copper and Monel metal.

Different kinds of work-engaging surfaces for furnace conveyor units have been suggested for inhibiting such pickup. In the case of the heat treatment of silicon steel, furnace rolls are being successfully used for that purpose with work-supporting portions of carbon in the presence of substantially non-oxidizing vor inert controlled atmospheres in the furnace as shown in my Patent Nos. 2,603,578 and 2,772,872. However, particularly when a furnace atmosphere is strongly reactive with respect to carbon (as, for example, when the dew point of such atmosphere is high), it has been discovered that such carbon tends to react to form a gas with corresponding disappearance of solid phase carbon, undue wear and untimely breakdown of the roll surface in some cases. That in turn limits the trouble-free period of operation in the furnace and increases maintenance expense and replacement cost.

In my present invention, I have been able to overcome the problem of undue wear and shortened life in furnace rolls or other furnace conveyor units and the like having a surface inhibiting pick-up on the work or the surface,

' even though the furnace atmosphere may be reactive with carbon. Other objects and advantages will be apparent from the following description and from the accompanying drawings, which are illustrative only, in which FIGURE 1 is a view of a furnace roll, partly in section through the axis of said roll, embodying my invention;

FIGURE 2 is a section of said roll taken along the line IIII of FIGURE 1;

FIGURE 3 is a partial and sectional view of a roller hearth in a furnace in which such rollers are provided with composite carbonaceous work-engaging members made in accordance with my invention;

FIG-URE 4 is a view of another kind of furnace conveyor unit assembly provided with preshaped composite carbonaceous members made in accordance with my invention;

FIGURE 5 is a view taken along line V V of FIG- URE 4;

FIGURE 6 is an illustrative chart showing reaction resistance advantages of anti-pickup carbon-and-metal work-engaging compositions of this invention; and

. particles in the amorphous or graphitic state particles I FIGURE 7 is a chart illustrating advantages which maybe secured by addition of bor-ic oxide as an addition ingredient.

Referring to FIGURES 1 and 2 of the drawings, there is shown a furnace conveyor unit 10 in the shape of a furnace roll having a body 11, laterally outwardly tapered necked portions 12 and journals 13 for mounting in any appropriate manner. Roll 10 is provided with a surfacing member 14 made in accordance with my invention. In the embodiment so illustrated, member 14 is in the form of a cylindrical sleeve having indentation recesses 15 around the edge of each end thereof. After member 14 is axially moved into position during the assembling of roll 10 to surround supporting bdoy 11, retainer rings 16 may be moved into engagement with the respective ends of sleeve 14 to secure it in place in roll 10, and a welding bead 17 being employable to lock the retainer rings 16 in place. If desired, one or both of such retainer rings 16 may instead be fastened to body 11 by holding or other means. Temperature resistant alloys are used preferably on exposed parts since a roll such as roll 10 may be employed in a furnace in which metal work passing therethrough is raised to a temperature as high in some cases as about 2000 F.

The retainer rings 16 may be provided with axially extending lugs 18 in spaced circumferential relation to each other, such spacing being such that the lugs 18 fit into the recesses 15 so that there is no relative movement in operation between surfacing member 14 and the remainder of furnace conveyor unit 10. It will be recognized that in some installations, other holding means may be employed if some relative rotational movement between the surfacing member and the remainder of the unit is to be permitted and, further, that in other installations, no need will arise or be desired for any positive keying relation between a surfacing member and the remainder of the unit. In some cases also, the interior of the body 11 may be cooled by a fluid introduced through axial passages in one or both ends of the unit.

One employment of furnace conveyor units like rolls 10 may be found in a roller hearth furnace 19, the interior furnace space of which would generally be surrounded by a refractory 20 while metal work 21 being treated in furnace 19 might progress through the furnace in the direction shown by the arrow While being supported on rollers 22 having a body 23 and a new surfacing member 24 of my invention. The rollers 22 may be idle or driven as desired, depending upon the means used to cause movement of the metal work 21 through the furnace. An even more likely present-day use of such furnace roll compositions of this invention will be in continuous heattreating tower furnaces for the processing of metal in strip or strand form at high temperatures.

The instant invention is particularly applicable to inhibiting the development of pick-up when the metal work 21 is of a ferrous metal composition such as silicon strip or stainless steel but the invention is not confined to such ferrous compositions and may also be applied to nonferrous metals. My invention further is resistant to untimely loss of weight of carbon in solid phase, and to change in shape or diameter of the work-supporting members like members 14 and 24 therefor. Thereby the respective units 10 and 22 have longer life and dimensional stability even when the controlled atmosphere used in the furnace interior may be reactive with carbon resulting in depletion of the element carbon in its solid phase in the member by conversion thereof into a gas.

Surfacing members, such as members '14 and 24, are composite carbonaceous members made essentially of an admixture of carbon and metal. Such a new oxidation and pickup resistant surfacing member to engage work may be manufactured, for example, by mixing carbon Patented June 5, 1%2v be in the form of an alloy or mixture with one another or with other preferential affinity metals having intermediate melting points such as calcium and/or magnesium. One source of such carbon may be petroleum coke which may be somewhat lower in cost compared to other sources of carbon.

Such mixture of carbon and metal may be shaped by mixing itwith a. binder preferably in the nature of a bituminous product like pitch or tar, whether with or without boric oxide therein, as the case may be. Then the admixture of carbon and metal and binder is molded or otherwise shaped into the desired shape which the new composite carbonaceous memberis to have. Such molding may be performed, for example, by extruding in the case of a cylindrical sleeve like surfacing members I4 and 24.. The shaped admixture may then be heated :ance of such carbon-and-metal to loss of weight due to any tendency to react with oxygen, whether as free oxygen or reactive oxygen-containing gases, in the furnace,

' when the boric oxide is present in amounts of about five parts by weight or more in a hundred parts of the entire mixture.

One of my new surfacing members maybe made up before curing, for example, in proportions of about 6 parts carbon from petroleum coke, about 2 parts silicon and about 2. parts bituminous tar, all on a weight basis, and yield a highly satisfactory composite carbonaceous member of this invention. Silicon may be in the form of a commercially pure powdered silicon or added in the form of an addition alloy like ferrosilicon or of a mixture such as calcium-silicon. Titanium, zirconium and chromium are other metals 1 have discovered to be advanta geous when used in accomplishing my invention and such is also the case with aluminum. Aluminum, however, appears to be more useful as a member component in situations where there is an absence of sulfur (such as occurs in some pitches and tars) when there is moisture in the atmosphere surrounding a new carbonaceous memto a temperature, for example, in the neighborhood or, I

1800 F. (or the expected furnace temperature) in the course of which it cures or hardens and its shape is set. If pitch or tar is used as a binder to 'bond thenew surface 1 member, thepitch or tar. is carbonized in the heating and.

becomes a part of the member. 1 a

After such shapingandcuring, my new surfacing member is assembled with the remainder of a furnace conveyor unit or the. like with which-it is to be used -as the, work-engaging surface thereof. carbonaceous member for such surfacing has been found to be relatively stable in dimensions and longer wearing. even in cases where thecontrolled atmosphere used in the furnace in which the member is employed causes some loss in weight by-reaction of such atmosphere with 7 the carbon in such member, any suchreaction occurring, moreover, at a slower rate than would be the case with a surfacing member ofcarbon alone. Even should any loss of carbon in such a new composite memberbegin to give an appearance of fporosity, the dimensions of the member and its ability to support the metal work it engages, remain for a relatively longer period of time. In addition, my new surfacing members inhibit develop-' ment of thephenomenon of pickup while exhibiting such resistance to wear, to change in dimension and to carbon loss deterioration.

Such a new composite her containing aluminum. In general, of the metals named above, silicon, titanium and zirconium are preferred. Boron oxide (B 0 when used, may also be added in the form of a commercial grade powder, preferably in a selected weight percentage amount between from about 5% to 40%.

Such a metal as silicon, titanium, zirconium, chromium and aluminum, with their preferential aflinity for oxygen relative to the atfinity of carbon for such oxygen at operative temperatures, may be used alone or as an alloy or mixture with one another, and/ or as an alloy or mixture with intermediate melting point preferential afiinity metals like calcium or magnesium, as the metal component in my new carbon-and-metal Work-engaging members. However, I have also discovered that relatively lower melting point metals with a preferential ailim'ty for oxygen greater than carbon, such as sodium, potassium and lithium in their elemental form, are not suitable for the manufacture of'my new composite members. Further, I have discovered that a metal like molybdenum, in which the oxide peratures generally used in a thereof is not relatively stable in the solid phase at temheat-treating furnace, also is not suitable. As used herein, the term preferential affinity metal refers to a metal having an afiinity for oxygen greater than that of carbon for such oxygen at furnace operating temperatures, such a metal or metals being It appears that my new composite carbonaceous members may be compoundedlwithoutclays or fillers. Corn-' ponents in such members may employed in a range by weight running from about8 parts of the metal and 2 parts of carbon inclusivefof anyresidue of a binder like pitch or tar, by weight, on the one hand, to about 1 part of metal, 7 parts of carbon in the form of coke or other carbon and 2 parts in the form of pitch or tar binder, on the other hand, with realization ofnew results ofthis invention. Good results occur, in a narrower range hand using between about 60% of metal, based on the combined weight of metal'and carbon (inclusive of any carbon left after curing from the bonding material used), and 15% of'metal based on the total weight of metal and. carbon. The quantity of binder originally added'prefer- 1 other than such aforesaid relatively lower melting point metals and other than a metal as aforesaid in which the oxide ofsuch metal is not a stable solid at such temperatures.

Lu FIGURE 4, a further form of furnace conveyor unit assembly is shown which may be employed and embody new composite carbonaceous members of my invention for engagement withmetal work carried by such assembly. Thus, conveyor assembly 25 is endless and 1 operates by movement in avertical plane in its furnace.

Furnace con eyor unit assembly 25 is provided with links 26 pinned at each end to an adjoining link 26 by a pin 27, the axes of which are horizontal. The upper side of each link 26 is flat and supports a body 28, the link being provided with a tappedand drilled hole 29 in regisably would be in the neighborhood of -about 20% of the i V combinedweight ofcarbon-and metal, andbinder in the' Original admixture and when the binder is bituminous it.

may be considered a part of the carbon component: In, general, a minimum of-20% of such combined Weight should be carbon.

try with an openingfifl extending through body 28. A recess 31 in the upper side fof body 28 engages a downward projection ofa composite carbonaceous work-engaging-member 32 made in acco'rdance with my invention. .Carbonaceous member 32 is provided with a centralopeningSB through which a headed bolt 34.passes downwardly, the lower end of bolt 34 being threaded to.

engage the hole 29when head 35 is. rotated by a socket wrench. Bolt 34- is shouldered at 36 to bear against the face of recess 31 on the metal body 28, thereby avoiding bolting pressure against the more frangible carbon-andmetal supporting member 3 2. .The upper face of mem-;

ber f32' may be provided witha recess for the seating of ported by the furnace conveyor unit body 28.

which in turn are supof this invention: Laboratory Test Examples (Reaction Resistance) Various laboratory test examples are included at this point to illustrate the marked reaction resistance and anti-pickup character of carbon-and-metal compositions Exposed Original Ingredients Atmosphere Dew- Dura- Weight After Test Cylinders in Test Area Weight (Weight (vol. percent) point tion Test (grns.)

(sq. in) (grns) percent) F.) (hours) A-phase (1) 20 pitch (control). 4.3 15.13 coke 1 d1ssoc.NH 05-70. 19 14.86. A(phse1)(2) 14. 86 -do 65-70---- 18 14.03.

con to A-phase (3) 14.03 d.o 85 18 disinte- I (control). grated.

B-phase (1) 4.9 15.22 do 65-70---- 19 15.17. B-phase (2) 15.17 d 65-70-.-- 18 14.48. B-phase (3)-- 14.48 d0 85 18 12.89. C (control) 6.32 23. 56 do 6074 64.5 disinttzez1 gra e D 6.32. 30.17 d0 65-74-.-- 641 23.93. E 5.4 31.14 do 60-74..-- 64.5 25.96. F 6.32 30. 90 do 6074 64.5 23.82.

GandH m G had 30. 27 do about 66- 166. 5 30.13. H (control) Same 27. 33 do about 00. 166.5 17.86.

area. Iv I 5.66- 33.73 90 NaHz 6070 48 35.07. J (control) 7.07- 48.43 coke 90 Nz10Hz- 50-70-"- 48 40.58.

1 All coke used was petroleum coke. Laboratory Test Examples (Pickup Resistance) 1 Composition of Work-En- Test Atmosphere Dewpolnt Duration Test gaging Cyl- Temp. (vol. Percent) F.) (hours) Result inder (weight F.)

Percent) carbon A 20 256811-- 1, 850 90Na-10H1.... 60 18 no pickup.

90N:-10H:. 16% D0.

8-1 Air-Gas.-- 60 16 Do.

8-1 Air-Gas-.. 60 16 Do.

8-1 Air-Gas--. 60 16 D0.

8-1 Air-Gas... 65 18 D0.

8-1 Air-Gas 65 18 D0.

Hz25N: 72 18 D0.

75H7-25N 72 18 D0.

N2-10H2 50 18 D0.

9ON:1OHz 50 18 DO.

90N210H:- 50 18 Do.

' 90N:|10Hz 65 18 D0.

90N51OH3 18 D0. 1,800 90N210Hz D0. 1,800 90N710H7.--. 70 18 D0. 1,800 sum-10112-". 70 13 Do. 1,800 7-1 DX 70 18 Do.

1, 000 90N110H,. 55 18 Do.

1 Silicon steel used in these tests.

FIGURE 6 also illustrates oxidation resistance of my carbon-and-metal members for respective metals used in increasing weight percentages in the combined weight of the tested mixture. Thus, solid line A represents the increasing oxidation resistance efiect of increasing amounts of silicon in a mixture, the balance of which was carbon in the form of graphite with a pitch binder, tested for eighteen hours at a temperature of 1800 F. in a 90% nitrogen-10% hydrogen atmosphere with a dew point .of

about 95 F. The long-dash'lin-e B in FIGURE 6 represents the oxidation resistance effect of increasing amounts of silicon in the admixture when tested at the same tern perature for the same period of time in an 8 to l air-gas atmosphere ('2. DX gas atmosphere having the following approximate volume percentages in its composition, 7.5 H 6.2 CO, 8.2 CO balance N with a dew point of about 60 F.

Chainline C on the FIGURE 6 chart illustratesthe improvement eitect of increasing weight percentage of chromium in a mixture with the balance graphite, inc1usive of 20% by weight of pitch binder, tested for eighteen hours at 1800 F. in a 90% nitrogen- 10% hydrogen 'atmosphere with a dew point of about 70 F. Short-dash line D in FIGURE 6 illustrates the advantage of increased titanium amounts on the oxidation reaction re- 1 sistance of a mixture having the'balance graphite, inclusive of 20% by weight of pitch binder, tested for eighteen hours at 1800 F. in a 90% nitrogen-10% hydrogen fatmosphere with a dewpoint of about 70 a The tests shown on FIGURE 7 illnstratebenents obtained by the addition of boron oxide (B as an ingredient in carbon-and-metal members of this invention. The FIGURE 7 tests of lines I and I' were conducted in air, a much more reactive atmosphere than would generally be encountered in a metal heating furnace utilizing conveyor unit or the like, comprising, in combination,

carbon and metal in shaped bonded admixture, said carbon being in the range from about 95% to about 20% by weight of the total weight of carbon and metal, said metal being in the range from about 5% to about 80% by weight of the total weight of carbon and metal, said metal further having apreferential afiinity relative to carbon at furnace temeperature for freeoxygen and reactive oxygencontaining gases, said metal still further having the ability to form stable solid predominantly non-alkaline oxide.

2. A work-engaging member for a heat treating furnace conveyor unit or the like, comprising, in combination, carbon and metal in an admixture of predetermined shape, said carbon being in the range from about 85% to about 40% of the totalweight of said member, said metal being in the range from about to about 60% of the total weight of said member, said metal being selected from the group consisting of silicon, titanium, Zirconium, chromium, aluminum and alloys and metal mixtures thereof in which at least one of said last-named metals predominates.

3. A work-engaging member as set forth in claim 2 in which said metal is silicon.

4. A work-engaging member as set forth in claim 2 in which said metal is titanium.

5. A work-engaging member as set forth in claim 2 in which said metal is-aluminum.

8. A Work-engaging member as set forth in claim 2 V in which said carbon and metal admixture is in the carbon-and-metal rolls of this invention. Line I in FIG- URE 7 represents the variable oxidation resistance of increasing amounts of silicon-magnesium alloy (52% Si- 31% Mg) with the mixture balance graphite, inclusive of of a pitch binder, tested for four hours at 1800 F. in air. However, when 5% by weight of B 0 was added to the compositions producing the line I test results, the boric oxide yielded test results summarized by line 1' showing marked benefits in the oxidation resistance of the carbon-and-Si-Mg mixtures. The weight percent scale for lines I and I refers to the percentage of siliconmagnesium alloy in the test specimens.

Further, in FIGURE 7, a reference point II represents a weight loss in grams per square inch of a test cylinder mixture containing silicon metal with the balance graphite, inclusive of a pitch binder, tested for eighteen hours at 1800 F. in a 90% nitrogen-10% hydrogen atmosphere with a dew point of about 95 F. The addition of boric oxide to such a mixture in increasing percentages ranging from 5% to 20% while retaining 25 silicon and the balance graphite and pitch, greatly improved oxidation resistance as shown by line II during testing of the specimens for sixty-nine hours at 1800 F. in a 90% nitrogen-10% hydrogen atmosphere with a dew point of about 60 F. The weight percen scale for line II refers to the percentage of boric oxidein the test specimens. Such beneficial efiects by the addition of bon'c oxide appear when it is an ingredient of the oarbon-andemetal mixture in a range, in general, from about 5% to about by weightof the total weight of the member, with the preferred addition quantity of such boron oxide being in the range of about 10% to about 20% of that total weight.

Various modifications in proportions of member components, in aspects of my invention as hereinabove outlined and as hereinafter claimed, may be made without departure from the spirit of my invention or the scope of range of. from about 95% to about 60% of the total weight of said member and in which from about 5% to about 40% by weight of boric oxide is present in the total weight of said member.

9. A work supporting unit for a heat treating furnace or the like, comprising, in combination, a supporting body,

, a work-engaging member supported by said body, said member consisting essentially ofa major proportion by weight of carbon in admixture with a minor proportion by weight of'one or more metals selected from aigroup consisting of silicon, titanium, zirconium, chromium, aluminum and alloys and metal mixtures thereof in which at least one of said last-named metals predominates.

10. -A supporting unit as set forth in claim 9 in which boron oxide is present in said admixture.

11. A support unit or the like for metal work subjected to elevated temperatures in an atmosphere containing reactive oxygen, comprising, in combination, a supporting body, a work-engaging member supported by said body, said member comprising a major proportion of carbon sufiicient to inhibit pick-up and a minor proportion of metal sufficient to inhibit reaction deterioration, said metal being characterized by its preferential affinity relative to carbon at such temperaturesfor any such reactive oxygen and its ability to form stable solid predominantly non-alkaline oxide thereby, said oxide having a melting point at least as high as said temperatures.

12. A support unit or the like as set forth in claim 11 V in which said member further comprises a quantity of boric oxide less by weight than said minor proportion.

of metal.

13. A support member to engage metal work at elevated temperatures being a bonded admixture of at least one metal characterized by its preferential affini-ty relative to carbon at such temperatures for any free oxygen and reactive oxygen-containing gases present and by its ability to form stable solid predominantly non-alkaline oxide'in any such gases, said oxide having a melting point not lower than such temperatures, said metal being in a sufficient quantity to inhibit deterioration of such member in any such gases, with the balance of said admixture being substantially carbon.

14. A support member as set forth in claim 13 in which said metal, further, is silicon.

15. A support member as set forth in claim 13 in which said metal, further, is titanium.

16. A support member as set forth in claim 13 in which said metal, further, is zirconium.

17. A support member as set forth in claim 13 in which said metal, further, is chromium.

18. A support member as set forth in claim 13 in which said metal, further, is aluminum.

19. A support member as set forth in claim 13 in which said metal is present in said admixture in an amount between about and about 60%, by weight.

20. A support member as set forth in claim 13 in which boric oxide is present in said admixture in an amount between about 5% and 30%, by weight, said amount being less than the amount of said metal present in said admixture.

21. In a process of subjecting metal work to heat-treating temperatures in an atmosphere having reactive oxygen therein, wherein members in supporting and guiding contact with such work are normally subject to at least one of two problems of pickup and deterioration through reaction with such oxygen, the improvement which comprises subjecting the work to such a temperature in the presence of such an atmosphere and contacting such work therein for support and guidance with a bonded admixture consisting essentially of a major proportion of carbon suificient to inhibit pickup and a minor proportion of metal sufficient to inhibit deterioration, said metal being characterized by its preferential afiinity relative to carbon at such temperatures for any such reactive oxygen and its ability to form stable solid predominantly non-alkaline oxide thereby, said oxide having a melting point at least as high as such temperatures.

22. In a process of subjecting metal work to heattreating temperatures in an atmosphere having reactive oxygen therein, wherein members in supporting and guiding contact with such work are normally subject to at least one of two problems of pickup and deterioration through reaction with such oxygen, the improvement which comprises subjecting the work to such a temperature in the presence of such an atmosphere and contacting such work therein for support and guidance with a bonded admixture consisting essentially of a major proportion of carbon suflicient to inhibit pickup and a minor proportion of metal and boron oxide sufiicient to inhibit deterioration and to increase the mechanical r strength of said bonded admixture, said metal being characterized by its preferential afiinity relative to carbon at such temperatures for any such reactive oxygen and its ability to form stable solid predominantly non-alkaline oxide thereby, said last-named oxide having a melting point at least as high as such a temperature.

23. In a process of subjecting metal work to heattreating temperatures in an atmosphere containing reactive oxygen, wherein members in supporting and guiding contact with such work are normally subject to at least one of two problems of pickup and deterioration through reaction with such oxygen, the improvement which comprises subjecting the work to such a temperature in the presence of such an atmosphere and contacting such work therein for support and guidance with a shaped member comprising essentially a suflicient amount of carbon to inhibit pickup in admixture a sufficient amount of metal to inhibit deterioration, said last-named metal being selected from the group consisting of silicon, titanium, zirconium, chromium, aluminum and alloys and metal mixtures thereof in which at least one of said last-named metals predominates.

24. In a process as set forth in claim 23, in which said last-named metal is silicon in a quantity at least about 5% by weight of metal and carbon.

25. In a process as set forth in claim 23, in which said last-named metal is titanium in a quantity at least about 5% by weight of metal and carbon.

26. In a process as set forth in claim 23, in which said last-named metal is zirconium in a quantity at least about 5% by weight of metal and carbon.

27. In a process as set forth in claim 23, in which said last-named metal is chromium in a quantity at least about 5% by weight of metal and carbon.

28. In a process as set forth in claim 23, in which said last-named metal is aluminum in a quantity at least about 5% by weight of metal and carbon.

29. In a process of making a work-engaging composition which inhibits pickup and reaction with free oxygen and reactive oxygen containing gases and supporting Work directly upon said composition in a high temperature industrial furnace, the steps comprising, mixing carbon and metal particles with a bonding substance present, said metal being selected from the group consisting of silicon, titanium, zirconium, chromium, aluminum and alloys and metal mixtures thereof in which at least one of said last-named metals predominates, molding said mixture to a desired shape, heating said molded mixture to a hardened bonded condition, and supporting work directly upon said molded mixture in said hardened bonded condition in a relatively high temperature industrial furnace for heat treating said work.

30. In a process of making a work-engaging composition which inhibits pickup and reaction with free oxygen and reactive oxygen-containing gases and supporting work directly upon said composition in a high temperature industrial furnace, the steps comprising, mixing carbon,

metal and boric oxide particles with a bonding substance present, said metal being selected from the group consisting of silicon, titanium, zirconium, chromium, aluminum and alloys and metal mixtures thereof in which at least one of said last-named metals predominates, molding said mixture to a desired shape, heating said molded mixture to a hardened bonded condition, said carbon being in an amount of at least 20 weight percent, said metal being present in an amount of at least 5 weight percent, said boric oxide being present in an amount of at least 5 weight percent, and supporting work directly upon said molded mixture in said hardened bonded condition in a relatively high temperature industrial furnace for heat treating said work.

References Cited in the file of this patent UNITED STATES PATENTS 1,923,036 Knopf Aug. 15, 1933 2,695,849 McMullen Nov. 30, 1954 UNITED STATES PA TENT OFFICE CERTIFICATE, OF CORRECTION Patent No. 3,037,756 June 5, 1962 Nathaniel B. Ornitz It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 14, for "bdoy" read body line l6 strike out "and"; line 20, for "holding" read bolting Signed and sealed this 11th day of September 1962.

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents 

1. A WORK-ENGAGING MEMBER FOR A HEAT TREATING FURNACE CONVEYOR UNIT OR THE LIKE, COMPRISING, IN COMBINATION, CARBON AND METAL IN SHAPED BONDED ADMIXTURE, SAID CARBON BEING IN THE RANGE FROM ABOUT 95% TO ABOUT 20% BY WEIGHT OF THE TOTAL WEIGHT OF CARBON AND METAL, SAID METAL BEING IN THE RANGE FROM ABOUT 5% TO ABOUT 80% BY WEIGHT OF THE TOTAL WEIGHT OF CARBON AND METAL, SAID METAL FURTHER HAVING A PREFERENTIALAFINITY RELATIVE TO CARBON AT FURNACE TEMPERATURE FOR FREE OXYGEN AND REACTIVE OXYGEN-CONTAINING GASES, SAID METAL STILL FURTHER HAVING THE ABILITY TO FORM STABLE SOLID PREDOMINANTLY NON-ALKALINE OXIDE. 